Network topology determines the availability and characteristics of the “connection” between any two nodes of the network. A “connection” is defined by the number of consecutive links forming the connection and the available transmission capacities of those links. These characteristics determine the data transmission reliability and delay between the “connected” network nodes.
For a network of fixed nodes, the topology is essentially static, being determined by the physical connections between the nodes. For a network with wireless mobile nodes, however, the topology is dynamic. In such ad hoc mobile networks, the topologies must be continuously managed in a self-forming manner by dynamically selecting from among multiple possible topology choices.
Current wireless network topology management technology employs network planning tools of the kind used with cellular communications networks. The utility of such planning tools, however, is limited to infrastructure networks, i.e. networks that include base stations operating with a single (generally omni-directional) type of radio. The ad hoc network, in contrast, is an infrastructure-less network in which the network elements (nodes) move around freely and the topology and networking conditions change continuously. Consequently, the network management tools designed for the reasonably static topologies and network conditions of the infrastructure networks are unsuited for application to the ad hoc mobile network dynamic environments.
Topology management in ad hoc dynamic environments is challenging for the following reasons: (1) the topology is highly dynamic and continuously changing due to the high mobility of the nodes; (2) the mobile nodes (platforms) are greatly varied, i.e. heterogeneous in nature, employing different types of radios with differing capabilities; and (3) the traffic is unbalanced with dynamically varying traffic distributed among different traffic types and priorities.
Disaster response to large-scale catastrophes, requiring the implementation of an information network to support the delivery of effective rescue services over a large area, presents a good example of an ad hoc dynamic environment that could benefit from the present invention. Such a network could include different types of land, sea, and/or air vehicles employing a random mix of commercially available wireless technologies, including such varied ones as Wi-Fi, Bluetooth, and UMTS-TDD Ad Hoc, among others. As such ad hoc communication devices abound, they come together in unplanned topologies, and when the networks become dense, as, for example, in an urban downtown, congestion and latency grow rapidly. A topology management system is required to dynamically set-up and manage such networks.
Another area that could benefit from the present invention is the US Department of Defense's (DoD's) pursuit of a comprehensive network-centric transformation of its forces. Initiatives such as the Navy FORCEnet and programs such as the Army Warfighter Information Network—Tactical (WIN-T) are central to this transformation. Such DoD efforts are predicated on the dynamic networking of radios with directional or omnidirectional antennas on a variety of platforms operating in a dynamic and ad hoc manner, and delivering over this network a variety of services with varying Qualities of Service (QoS) and multiple levels of security.
A method for managing ad hoc networks with directional antennas was disclosed in U.S. Pat. No. 7,830,820 B2, “Method and Apparatus for Directional Networking Topology Management,” issued to Duke et al. A number of systems for managing antenna connection parameters in order to control the topology have also been disclosed (See, e.g. U.S. Pat. No. 6,990,080 B2, “Distributed Topology Control for Wireless Multi-hot Sensor Networks,” Bahl et al.; US Patent Application No. US 2007/0081556 A1, “Antenna Management System,” Evans et al.; and US Patent Application No. US 2007/0195746 A1, “Topology Management, Power Control and Cross-layer Design for Wireless Mobile Ad Hoc Networks with Directional Antennas,” Ryu et al.) All these inventions, however, have focused on forming and managing antenna connectivity in the neighborhood of a node, and the topologies they form have been based on neighborhood connection considerations that fail to take into account the network-wide traffic loads and patterns. These are serious limitations, since such topology formations are ill-suited to supporting ad hoc networks with dynamically changing network traffic loads and patterns.
Topology management for establishing connectivity on the basis of the local traffic load has been disclosed in U.S. Pat. No. 7,855,997 B2, “Long Range Scheduling for Directional Antenna MANET Networks,” issued to Adams et al. These traffic scheduling and connectivity considerations, however, are also, as above, limited to the immediate neighborhood of the node, failing to take into account the network-wide traffic loads and patterns. Furthermore, packet priorities are not factored into scheduling the forwarding of the data packets. These constitute serious limitations since traffic load increases elsewhere in the network can potentially impact the delivery of the local packet, for example, where a congested area is en-route the packet's transit path. Also, where the topology management fails to treat high priority packets preferentially, their delivery reliability and latency performance suffer.
Methods that implement topological connectivity over the entire network have also been disclosed. (See, e.g., U.S. Pat. No. 6,791,949 B1, “Network Protocol for Wireless Ad Hoc Networks,” Ryu et al.; U.S. Pat. No. 7,606,171 B1, “Skeletal Node Rules for Connected Dominating Set in Ad-Hoc Networks,” Young et al.; US Patent Application No. 2011/0090787 A1, “Spanning Tree Flooding Backbone Systems and Methods for Link State Routed Networks,” Smith et al.) As above, however, these methods too do not take into account the network-wide traffic loads and patterns and data packet priorities.
Preferential scheduling of higher priority packets at a network node has been disclosed in U.S. Pat. No. 7,417,999 B1, “Priority Propagation in a Multi-level Scheduling Hierarchy,” issued to Charny et al. But this patent only addresses priority-based transmission of data packets at a single node, and not across the network. This approach too, as above, fails to take into account the specifics of the network topology in formulating the forwarding strategy, and the packet forwarding strategy implemented may not be supportable by the prevailing topology.
There exists a need for a topology management system and method that manages network-wide topology and influences data packet forwarding based on the traffic loads, patterns, and priorities across the network. This requires a topology management system that dynamically tracks the network traffic characteristics and forms and manages the topologies accordingly. The system and method disclosed and claimed herein provide an effective means to dynamically manage topology and network performance in such scenarios.